Toleikis 2020 Cells

From Bioblast
Publications in the MiPMap
Toleikis A, Trumbeckaite S, Liobikas J, Pauziene N, Kursvietiene L, Kopustinskiene DM (2020) Fatty acid oxidation and mitochondrial morphology changes as key modulators of the affinity for ADP in rat heart mitochondria. Cells 9:340.

Β» PMID: 32024170 Open Access

Toleikis A, Trumbeckaite S, Liobikas J, Pauziene N, Kursvietiene L, Kopustinskiene DM (2020) Cells

Abstract: Fatty acids are the main respiratory substrates important for cardiac function, and their oxidation is altered during various chronic disorders. We investigated the mechanism of fatty acid-oxidation-induced changes and their relations with mitochondrial morphology and ADP/ATP carrier conformation on the kinetics of the regulation of mitochondrial respiration in rat skinned cardiac fibers. Saturated and unsaturated, activated and not activated, long and medium chain, fatty acids similarly decreased the apparent KmADP. Addition of 5% dextran T-70 to mimic the oncotic pressure of the cellular cytoplasm markedly increased the low apparent KmADP value of mitochondria in cardiac fibers respiring on palmitoyl-l-carnitine or octanoyl-l-carnitine, but did not affect the high apparent KmADP of mitochondria respiring on pyruvate and malate. Electron microscopy revealed that palmitoyl-l-carnitine oxidation-induced changes in the mitochondrial ultrastructure (preventable by dextran) are similar to those induced by carboxyatractyloside. Our data suggest that a fatty acid oxidation-induced conformational change of the adenosine diphosphate (ADP)/adenosine triphosphate (ATP) carrier (M-state to C-state, condensed to orthodox mitochondria) may affect the oxidative phosphorylation affinity for ADP.

β€’ Bioblast editor: Gnaiger E

Toleikis 2020 Cells CORRECTION.png

Correction: FADH2 and Complex II

Ambiguity alert.png
FADH2 is shown as the substrate feeding electrons into Complex II (CII). This is wrong and requires correction - for details see Gnaiger (2024).
Gnaiger E (2024) Complex II ambiguities ― FADH2 in the electron transfer system. J Biol Chem 300:105470. - Β»Bioblast linkΒ«

Hydrogen ion ambiguities in the electron transfer system

Communicated by Gnaiger E (2023-10-08) last update 2023-11-10
Electron (e-) transfer linked to hydrogen ion (hydron; H+) transfer is a fundamental concept in the field of bioenergetics, critical for understanding redox-coupled energy transformations.
Ambiguity alert H+.png
However, the current literature contains inconsistencies regarding H+ formation on the negative side of bioenergetic membranes, such as the matrix side of the mitochondrial inner membrane, when NADH is oxidized during oxidative phosphorylation (OXPHOS). Ambiguities arise when examining the oxidation of NADH by respiratory Complex I or succinate by Complex II.
Ambiguity alert e-.png
Oxidation of NADH or succinate involves a two-electron transfer of 2{H++e-} to FMN or FAD, respectively. Figures indicating a single electron e- transferred from NADH or succinate lack accuracy.
Ambiguity alert NAD.png
The oxidized NAD+ is distinguished from NAD indicating nicotinamide adenine dinucleotide independent of oxidation state.
NADH + H+ β†’ NAD+ +2{H++e-} is the oxidation half-reaction in this H+-linked electron transfer represented as 2{H++e-} (Gnaiger 2023). Putative H+ formation shown as NADH β†’ NAD+ + H+ conflicts with chemiosmotic coupling stoichiometries between H+ translocation across the coupling membrane and electron transfer to oxygen. Ensuring clarity in this complex field is imperative to tackle the apparent ambiguity crisis and prevent confusion, particularly in light of the increasing number of interdisciplinary publications on bioenergetics concerning diagnostic and clinical applications of OXPHOS analysis.

Labels: MiParea: Respiration 

Enzyme: Complex II;succinate dehydrogenase 


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